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Abstract Using Fisher information matrices, we forecast the uncertaintiesσMon the measurement of a “Planet X” at heliocentric distancedXvia its tidal gravitational field’s action on the known planets. Using planetary measurements currently in hand, including ranging from the Juno, Cassini, and Mars-orbiting spacecraft, we forecast a median uncertainty (over all sky positions) of A 5σdetection of a 5M⊕Planet X atdX= 400 au should be possible over the full sky but over only 5% of the sky atdX= 800 au. The gravity of an undiscovered Earth- or Mars-mass object should be detectable over 90% of the sky to a distance of 260 or 120 au, respectively. Upcoming Mars ranging improves these limits only slightly. We also investigate the power of high-precision astrometry of ≈8000 Jovian Trojans over the 2023–2035 period from the upcoming Legacy Survey of Space and Time (LSST). We find that the dominant systematic errors in optical Trojan astrometry (photocenter motion, nongravitational forces, and differential chromatic refraction) can be solved internally with minimal loss of information. The Trojan data allow cross-checks with Juno/Cassini/Mars ranging, but do not significantly improve the best achievableσMvalues until they are ≳10× more accurate than expected from LSST. The ultimate limiting factor in searches for a Planet X tidal field is confusion with the tidal field created by the fluctuating quadrupole moment of the Kuiper Belt as its members orbit. This background will not, however, become the dominant source of uncertainty until the data get substantially better than they are today.
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An Automated Occultation Network for Gravitational Mapping of the Trans-Neptunian Solar System
Abstract We explore the potential of an array of small fixed telescopes, aligned along a meridian and automated to measure millions of occultations of Gaia stars by minor planets, to constrain gravitational signatures from a “Planet X” mass in the outer solar system. The accuracy of center-of-mass tracking of occulters is limited by photon noise, uncertainties in asteroid shapes, and Gaia’s astrometry of the occulted stars. Using both parametric calculations and survey simulations, we assess the total information obtainable from occultation measurements of main-belt asteroids (MBAs), Jovian Trojans, and trans-Neptunian objects (TNOs). We find that MBAs are the optimal target population due to their higher occultation rates and abundance of objects above Legacy Survey of Space and Time detection thresholds. A 10 yr survey of occultations by MBAs and Trojans using an array of 200 40 cm telescopes at 5 km separation would achieve 5σsensitivity to the gravitational tidal field of a 5M⊕Planet X at 800 au for >90% of potential sky locations. This configuration corresponds to an initial cost of ≈$15 million. While the survey's sensitivity to tidal forces improves rapidly with increasing number of telescopes, sensitivity to a Planet X becomes limited by degeneracy with the uncertain masses of large moonless TNOs. The 200-telescope survey would additionally detect ≈1800 TNO occultations, providing detailed shape, size, and albedo information. It would also measure the Yarkovsky effect on many individual MBAs, measure masses of many asteroids involved in mutual gravitational deflections, and enable better searches for primordial black holes and departures from general relativity.
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- Award ID(s):
- 2205808
- PAR ID:
- 10567600
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Planetary Science Journal
- Volume:
- 6
- Issue:
- 1
- ISSN:
- 2632-3338
- Format(s):
- Medium: X Size: Article No. 19
- Size(s):
- Article No. 19
- Sponsoring Org:
- National Science Foundation
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